KRT5 and neoplasm: Some immunohistochemistry studies have found strong staining for p63 and high-molecular-weight cytokeratin (CK5/6) with a specificity of 99% and a sensitivity of 98% for squamous cell carcinoma [5, 10]; we had four patients who underwent immunohistochemical examination; the tumor cells had positive immunoreactivity for p63 and CK5/6, supporting the diagnosis of SCC.